<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
    <title>登录</title>
</head>
<body>
<div class="container" style="margin-top:200px;">
    <div class="col-md-4"></div>
    <form class="form-horizontal col-md-4">
  <div class="form-group">
    <label for="inputEmail3" class="col-sm-3 control-label">用户名</label>
    <div class="col-sm-9">
      <input type="email" class="form-control" id="inputEmail3" placeholder="用户名">
    </div>
  </div>
  <div class="form-group">
    <label for="inputPassword3" class="col-sm-3 control-label">密码</label>
    <div class="col-sm-9">
      <input type="password" class="form-control" id="inputPassword3" placeholder="密码">
    </div>
  </div>
  <div class="form-group">
    <div class="col-sm-offset-2 col-sm-10">
      <div class="checkbox">
        <label>
          <input type="checkbox"> Remember me
        </label>
      </div>
    </div>
  </div>
  <div class="form-group">
    <div class="col-sm-offset-2 col-sm-10">
      <button type="submit" class="btn btn-default">Sign in</button>
    </div>
  </div>
</form>
    <div class="col-md-4"></div>
</div>
</body>
</html>